The present invention relates to a liquid crystal display device used for a display screen in a word processor, a notebook computer, a portable equipment or a device.
In recent years, there have been manufactured a number of liquid crystal display devices as portable, thin and low electric consumption type display devices. As a method for mounting these products, there have been produced a system using zebra rubber, a system using a heat seal and a TAB system with a liquid crystal driving driver mounted on a film substrate in large numbers. Because of a strong request for reducing costs, however, a COG mounting system for directly mounting ICs on a liquid crystal panel has begun to be mainly used. As a method for mounting ICs on a glass substrate, there are available methods using an anisotropic conductive film, Ag paste, a contractile resin, etc. An electric signal is supplied to an IC connected to a glass substrate by using a film substrate, but in a liquid crystal display device with two or more ICs mounted on at least a side thereof, as described in Japanese Unexamined Patent Publications Nos. 4-184322 and 6-75240, a projected electrode was formed on the film substrate by means of printing or plating and connected to an input wiring formed on the glass substrate. Otherwise, input wirings for ICs were continuously formed in an external direction without any changes and a film substrate having two surface wirings was connected thereto.
In the liquid crystal display device disclosed in Unexamined Patent Publication No. 4-184322 or 6-75240, it was necessary to make an external dimension of the liquid crystal panel larger by an amount equivalent to a width of FPC. It is difficult to make a wiring width of an FPC electrode finer because of noises and connection accuracy with the liquid crystal panel and though the number of wirings depend on specifications of a driver IC, the external dimension of the liquid crystal panel cannot be reduced without reducing the number of signals input to the driver IC. Because of these reasons, it was difficult to reduce the external dimension of the liquid crystal display device. Also, since it was necessary to give special treatments to the film substrate, prices of the film substrates small in mass-produced number remained high, making it difficult to reduce costs as a liquid crystal display device. In the system using the two-surface wiring film substrate, since it was necessary to have processes for bending FPC after being connected and fixing this in a bent state in order to reduce the external dimension of the liquid crystal display device and an end of the external dimension was FPC, it was difficult to hold the liquid crystal display device.